1. Technical Field
The present disclosure generally relates to firearms. More specifically, the present disclosure relates to a bolt assembly and bolt carrier assembly with switch mechanism that enables discharging of spent bullet casings from either the left side or the right side of the rifle receiver without the need of disassembling the firearm.
2. Description of Related Art
Presently there are several approaches that enable firearms to discharge spent bullet casings, or cartridges, from either of both sides of the firearm. However, there are one or more shortcomings associated with each of these approaches, including the need to disassemble the firearm for reconfiguration to enable the discharging of spent casings from one side of the firearm to the other.
A first approach, described in Swiss Patent No. CH580269A, relates to a bullpup rifle designed for the purpose of discharging spent casings from either of both sides of the firearm. This approach uses a multi-lug rotating bolt design. Although this approach allows the change of direction out of which spent casings are discharged, disassembling of the firearm is necessary to reconfigure the firearm to enable the discharging of spent casings from one side of the firearm to the other.
A second approach, described in U.S. Pat. No. 7,331,135B2, relates to a bullpup rifle designed for the purpose of discharging spent casings from either of both sides of the firearm. Similarly, this approach uses a multi-lug rotating bolt design. Although this approach allows the change of direction out of which spent casings are discharged, disassembling of the firearm is necessary to reconfigure the firearm to enable the discharging of spent casings from one side of the firearm to the other.
A third approach, described in U.S. Pat. No. 5,675,924, relates to a bullpup rifle designed for the purpose of discharging spent casings to the front of the firearm. Accordingly, this approach does not require any adjustment of the firearm when an operator changes from left-hand firing to right-hand firing of the firearm, and vice versa. This may be preferable to other designs from the perspective of ease for the operator's selection and changing of the firing hand. However, such design tends to retain some spent casings inside the firearm, thereby introducing higher possibility of jamming the firearm. Furthermore, as this design has less open port on the firearm receiver, when jamming does occur it is very difficult for the operator to access the jammed casing and clear the jam.
A fourth approach, described in U.S. Pat. Nos. 7,849,777, 7,819,052 and 7,395,626 and U.S. Patent Application Publication No. 20100300278, relates to a conventional rifle design with a stock. This approach allows spent casings to be discharged from either the left side or the right side of the firearm by the operator pushing a switch mechanism located inside the firearm with a tool. No disassembling of the rifle is necessary. The tool may be a screw driver or a rifle ammo cartridge, for example. However, those tools are not necessarily installed on the firearm. This approach uses a multi-lug rotating bolt design and tends to have quite an amount of material at the bolt head machined away to allow switching of the discharging side to be possible. Therefore, the bolt head strength may be unnecessarily weakened.
A fifth approach, described in U.S. Pat. No. 3,882,625, relates to a bullpup rifle designed for the purpose of discharging spent casings from either of both sides of the firearm. This approach uses a multi-lug rotating design. However, although the direction in which spent casings are discharged can be switched, disassembling of the firearm is necessary.
The standard AR15 design includes a bolt assembly and a bolt carrier assembly with the bolt assembly disposed inside the bolt carrier assembly. FIG. 1A illustrates a standard AR15 bolt assembly 10 which comprises cam pin hole 11, extractor 12, multi-lug bolt head 13, ejector 14 and reinforcement lug 15. FIG. 1B illustrates a standard AR15 barrel extension 20 which comprises eight locking lugs 21. In order to avoid obscuring the illustration and to promote better viewing, certain components are not illustrated such as, for example, extractor pin, ejector spring, ejector retaining pin, etc. The bolt assembly 10 is assembled and disposed inside a bolt carrier. The bolt assembly 10 uses a multi-lug bolt head 13, with seven evenly-distributed lugs (with the eighth one missing in exchange of extractor slot), to lock with seven out of eight available locking lugs 21 on a barrel extension 20 when firing. After firing, the bolt assembly 10 will turn 22.5 degrees under the guide of the cam pin on the bolt carrier (not shown) through the cam pin hole 11, such that it will unlock with the barrel extension 20 to allow the spent bullet casing to be extracted by the extractor 12 and ejected from the rifle receiver by the ejector 14. The direction of ejection is from the ejector position pointing toward the extractor position.
The AR15 bolt assembly 10, looking in the direction from head to tail, is like a gear with eight square teeth. On the extractor slot where the extractor 12 is resided, one tooth is missing from the bolt body. However, the reinforcement lug 15 on the extractor 12 is positioned at the location of the missing locking lug, with somewhat shortened height. Hence, with necessary enhanced design, it is possible to use another gear-shaped piece to turn the bolt assembly according to its axis to change the ejection direction of the spent bullet casing.
However, standard AR15 can only allow spent casings to eject from the right side of the rifle. This is due to the fact that the cam pin hole 11 is restricted by the cam pin (not shown) sliding inside a groove on the upper receiver (not shown) of the rifle. Some custom made AR15 can be made to only allow the spent casing to eject from the left side of the rifle. Interchanging the ejection direction on such rifle, however, is not possible.